1. Field of the Invention
The present invention relates to a zoom lens, a camera device and a personal digital assistant.
2. Description of the Related Art
Along with the increased popularity of digital cameras, users demand relative to a digital camera not only a high-quality image and a reduced size, but also a photographing lens having a high magnification ratio. As the high magnification ratio of the zoom lens for use as the photographing lens, 4 times or more is demanded. In addition, a user also demands a photographing lens having a wide angle of view. As a half angle of view at the wide angle end of the zoom lens for use as the photographing lens, 35 degrees or more is demanded.
Conventionally, a zoom lens described in each of JP S60-87312A, JP H02-48088A and JP2001-183585A has been known as a zoom lens in which four groups having a negative focal length, a positive focal length, a negative focal length and a positive focal length are arranged from an object side. However, each of the zoom lenses has a magnification ratio of about 3 times, so it can not meet the recent demand regarding a magnification ratio of a zoom lens for a digital camera.
In addition, generally, in a zoom lens for a digital camera, an exit pupil position is limited severer than that for a silver salt camera because a CCD is used as an imaging element. For this reason, it is necessary for the exit pupil position to have about −20 mm to −100 mm in the whole zooming area. The compensation of the exit pupil position in the group nearest to the image side is especially, important. Since the fluctuation of the exit pupil position increases as the magnification ratio increases, the need for the above compensation further increases.